False advertising on website

I purchased a vacuum cleaner online for R999, with my 15% discount I paid R892.75. I ordered on line for the purpose that its coinvent and I dont have to drive around. The delivery was marked for Thursday. Thursday evening I get a call to say that the vacuum advertised and that i ALREADY bought was no longer in stock and i need to choose another one. A gentlemen by the name of Wesley assisted me and doing a awesome job of trying to find another product that will fit my needs. This was friday. But now the problem is I cant get one at the same price i bought. So now i have to pay MORE, I get a call Saturday to say I need to now ride in and pay in another R699 by a builders to complete my order. I said to the guy how the heck is that possible. If i purchase online i still get a 15% discount on R1499. he calculates, i must still pay in R499. I dont understand this. So now i must ride (after i said i dont want to) to pay an amount that is incorrect. For a product i didnt order in the first place. Come on builders fix this. Im so annoyed. I just want a vacuum, is that so hard